People are confusing regression testing definition with its meaning and approach
although they look like similar but there are few minor changes on regression testing meaning and
approaches which are shown below.

Regression
Testing Definition with Example

Checking that fixed bug do not affect the other sections of the modules by checking the functionality and other scenarios
of testing on different modules and within the similar module in which bug
is fixed is known as regression testing.

Note:
Do not confuse regression testing with re-testing because in re-testing tester
only test whether the fixed bug is getting fixed or not by re-testing it.